Bringing Historic Maps into GIS Patrick Florance Digital Cartographer Harvard Map Collection Harvard University.
Download ReportTranscript Bringing Historic Maps into GIS Patrick Florance Digital Cartographer Harvard Map Collection Harvard University.
Bringing Historic Maps into GIS Patrick Florance Digital Cartographer Harvard Map Collection Harvard University Purpose • Demonstrate how historical maps can be used within a GIS. • Illustrate the techniques used to bring historical maps into GIS • Show types of maps that are useful to bring into GIS • Convey research conducted at the Harvard Map Collection GIS • A geographic information system (GIS) is a configuration of computer hardware, software, and personnel specifically designed for the acquisition, maintenance, and use of geographically referenced data. Modification of Dana Tomlin’s definition Geographic Information Systems and Cartographic Modeling (1990) Why bring historic maps into GIS? • Use historic maps within GIS as a tool for understanding the spatial relationships of past phenomena – Deforestation – Shoreline change – Socio-economic characteristics of a state or a neighborhood – Place-names – Railroads and transportation networks – Disease Why bring historic maps into GIS? • Context: What exists within one’s study area at a given point(s) in time? – Overlay modern GIS data over historic maps – Early 20th century USGS topographic map of central Mass. Why bring historic maps into GIS? • Context: What exists within one’s study area at a given point(s) in time? – Overlay modern GIS data over historic maps – Early 20th century USGS topographic map of central Mass. – Overlay modern Quabbin Reservoir in semi-transparent blue Why bring historic maps into GIS? • Context: What exists within one’s study area at a given point(s) in time? Close up of northern Quabbin over early USGS topographic map. Features flooded: Towns, roads, railroads, etc. Why bring historic maps into GIS? • Feature Extraction (heads-up digitizing) and encoding – Vectorize: discrete data made up of ordered lists of points and represented by points, lines, and polygons – Trace features and encode those graphics with information – Surface of the earth Anthropogenic features Places, place-names, roads, railways, trails, buildings, bridges, etc. Natural features Rivers, lakes, shoreline, elevation, etc. Abstract/Administrative geography Country, state/province, municipal, parcel/property boundaries, census tracts, etc. Why bring historic maps into GIS? • Feature Extraction (vectorization) – 1898 USGS topographic map of Portland, Maine Why bring historic maps into GIS? • Feature Extraction (vectorization) – – – – 1898 USGS topographic map of Portland, Maine Built area extracted (vectorized) in red. Perhaps trace roads, railroads, shoreline, contours, etc. Note edge. Why bring historic maps into GIS? • Resource/Research Management Tool – More and more researchers using spreadsheets to manage their research to collect information about places and source material – Think of GIS as sort of a spatial spreadsheet or database, which can be used to join that information to spatial representations Why bring historic maps into GIS? • Analysis – Simple • Finding inns that are located within 5 miles of towns with a population over 10,000 in southern France around 1910. – More complex • Archaeological predictive modeling • Spatial analysis techniques to model fire density or disease patterns Why bring historic maps into GIS? • Analysis Interpolated fire density of Constantinople, 1660. Why bring historic maps into GIS? • Graphic presentations or visualization – Make maps, charts, graphs, etc. – Very powerful and useful – See David Rumsey Example Historic Map as a GIS Data Source • Historic maps are made for communicating, not for serving as a basemap/source data for a modern GIS. • Positional accuracy: features often moved slightly for clarity (i.e., clustered places, roads along rivers, etc.) • Scale distortion • Edge-matching • Insets • Paper streets • 1890 map vs. 1990 map Data Conversion/Development Process • Convert maps to digital form • Georeference the digital maps: assign them meaningful spatial coordinates • Feature extraction and data modeling ($$) – Generally around 80% of project cost – Heavy overhead before one gets results, which is one of reasons why so many GIS fail. Convert Printed Map to Digital Image • Digital Image (Raster) is composed of a grid of pixels 1898 U.S. railroad map Convert Printed Map to Digital Image Equipment • Large-format scanner – Expensive – Scarce • Overhead digital photography • Be careful using photocopies – Distortion along edges Convert Printed Map to Digital Image Resolution • Resolution can be expressed as the number of pixels per inch (PPI) • Different from spatial resolution of remotely sensed imagery, which is a measure of the smallest object that can be resolved by the sensor or the dimension on the ground represented by each pixel (i.e., 30 meters) Convert Printed Map to Digital Image Resolution (Cont.) • Generally between 150 - 600 ppi, average 200 - 300 ppi • Determine resolution that captures the smallest significant feature • Use consistent resolution if working with a map series • Capture uncompressed as TIFF (Tagged Image File Format) • Consider using image compression for working file • If map is in grayscale, capture it in grayscale color model – reduce file size • If map repository, consider capturing very high quality for archiving & resampling to lower resolution for GIS work Georeference the Digital Image/Map • Georeferencing converts a digital image (raster dataset) from a nonreal-world coordinate system (image space) to a realworld coordinate system such as latitude and longitude. • Makes it “line up” with other GIS data. • Allows the digital map image to be viewed with other GIS data. Georeferencing Process • Need to know locations of at least 3 recognizable features • Use more than 3 • Locations used to create control points • Spread out throughout the map 1898 U.S. railroad map Georeferencing Process • Need to know locations of at least 3 recognizable features • Use more than 3 • Locations used to create control points • Spread out throughout the map • Link real-world coordinates to the control points • Links used to transform the map image to real-world coordinates Lat/Long Lat/Long Lat/Long Georeferencing: Transformation • Transformation adjusts the digital map to make it fit in this real-world coordinate system • Affine Transformation - most common – – – – Scale Skew Rotation Shift (Translation) Affine Transformation: Scale • Changes the image scale by expanding or reducing Affine Transformation: Skew Before After X Y Affine Transformation: Rotation • Rotates x and y axes so that the image is correctly oriented Before After X Y Affine Transformation: Shift (Translation) • X and Y origin are shifted Before After X Y Georeferencing: Transformation Complete 1898 railroad map with modern vector shoreline overlaid • Software creates associated files that contain the coordinate information (i.e., .tfw) • Digital map can then integrated with other GIS data Root Mean Square (RMS) error • Root Mean Square (RMS) error – Describes the deviation between the control points in the output image and the values calculated by the transformation – A measure of the accuracy of the control points – In general, lower number the better, with 0 being perfect – Record RMS error – Save control points Georeferencing Techniques for Historic Maps • Use existing coordinates or tics • Link features on map to features within GIS datasets that have known real-world coordinates. • Global Positioning System (GPS) Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Over 134 types of features: towns, municipal boundaries, road types, railways, hydrology, rice fields, pasture land, post offices, churches, castles, inns, etc. Austro-Hungarian Monarchy Topographic Series, Scale: 1:75,000; Date: 1874-1912 Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Topographic map misaligned with modern GIS municipal boundaries (red) Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates • Step 1: map research – Map projection: polyhedric projection (antiquated) – Coordinate system: Bessel 1841 spheroid • Spheroid: estimated shape of the earth as a sphere – Prime meridian: Ferro – Metadata is often located on the topographic map itself • However, not in this case – Significant role for the historian Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates • Step 2: Create a point layer – From geographic coordinates of the 4 corners – Based on the historic coordinate system (Bessel 1841) and prime meridian (Ferro) Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates • Step 3: Project points into the historic map projection – Polyhedric antiquated – Used a polyconic Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates • Step 4: Link tic marks on the map to the projected corner points. Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates • Step 5: Transform the map Georeferenced topo with modern GIS municipal boundaries and rivers overlaid Use Existing Coordinates or Tics to Reference the Map in Real-World Coordinates Close up: modern municipal boundaries (gemeinden) overlaid on topo • Disparate datasets never match up perfectly • Off by around 300-400 feet • Detail on map: churches, road types, pastures, etc. Issue: study area falls on edge of a topo sheet Area Obscured by Overlap Mosaic: Match Adjoining Map Sheets • • Image processing software – Adobe Photoshop – ERDAS Imagine – ArcGIS Spatial Analyst Time consuming Other Useful Maps with Coordinate Systems • Topographic series – – – – USGS 1890s – 1950s: 1:62500 England & Wales: 1805-1874, 1:63,360 German Karte des Deutschen Reiches: 1862-1907; 1:100,000 China Ministry of National Defense Land Survey: 1901-1947; 1:100,000 – Survey of India: 1866-1910; 1:253,440. • Nautical charts – Shorelines, soundings, etc. • World and regional maps – Historic places, national and provincial boundaries, transportation networks, etc. • Globes Georeferencing Techniques for Historic Maps • Use existing coordinates or tics • Link features on map to features within GIS datasets that have known real-world coordinates • Global Positioning System (GPS) Feature Linking Use control points to link features on the map to features within a GIS dataset that have known real-world coordinates 2001 MassGIS Digital Orthophoto 1797 Street Map of Boston Feature Linking Steps • Acquire GIS reference dataset to link the map to – Should be of equal or slightly better scale • Map research – Map projection, coordinate system/datum – Identify additional map sources for reference • Establish reference points to use as links – Cultural features such as street intersections, bridges, buildings, landmarks, monuments, etc. – Try to avoid using natural features such as shoreline, rivers, lakes, etc. because they fluctuate greatly – Check dates of features on the map used as links • Project GIS data to match the projection of the map Feature Linking Steps (Cont.) • If georeferencing multiple maps, start with the most current map and work backwards in time – Provides more features to link to 1797 1835 1895 2001 Feature Linking Steps (Cont.) • Add at least 3 control points spread out throughout the map • Transform the map 2001 MassGIS Digital Orthophoto 1797 Street Map of Boston City-Wide Maps: Boston • Useful for tracing the historical development of: – Streets – Districts & wards – Shoreline – Town boundaries – Monuments – Churches – Schools – Significant buildings 1797 - 2001 shoreline change City-Wide Maps: Cambridge Full View 1865 street map of the City of Cambridge, MA City-Wide Maps: Cambridge Detail Detail of 1865 street map of the City of Cambridge, MA City-Wide Maps Georeferenced • Georeferenced 1865 map of Cambridge • GIS reference data – City of Cambrige GIS street centerline (shown in red) Integrate Additional GIS Data with Georeferenced Map Georeferenced 1865 map of Cambridge overlaid with 3D buildings Integrate Additional GIS Data with Georeferenced Map Georeferenced 1865 map of Cambridge overlaid with 3D buildings and modern shoreline of the Charles River Urban/Fire Insurance Atlases • Publishers: Bromley, Beers, Hopkins, Sanborn, Ordnance Survey (OS) • Begin around mid 19th century, early 1800s for OS. • Scale of 1:5000 or better • Wealth of information – Property: boundaries, owners, addresses – Building: footprints, composition, heights, stories, use, roof types – Other info: streets, fire hydrants, etc. Urban/Fire Insurance Atlases Detail Detail of 1867 Boston Sanborn Urban/Fire Insurance Atlases Full View • Issues – Bound editions make digital conversion difficult – Insets – Mosaicing or edgematching Ungeoreferenced 1867 Boston Sanborn Urban/Fire Insurance Atlases Georeferenced Mosaic Full View Georeferenced 1867 Boston Sanborn with inset mosaiced Urban/Fire Insurance Atlases Georeferenced Mosaic Detail Georeferenced 1867 Boston Sanborn with inset mosaiced Urban/Fire Insurance Atlases Integration of Modern and Historical Data Georeferenced 1867 Boston Sanborn with modern buildings overlaid in red Reconstructing the New Orleans Yellow Fever Epidemic of 1878 Andrew Curtis & John Anderson, LSU • Example of using historic urban atlases and city-wide maps • Textual descriptions • Automated data conversion • Historical geocoding of death residences • Spatial Analysis Other Useful Types of Maps • Census Maps – Most common request – Enormous amount of vectorization work – Scarce Minor Civil Divisions, NY, 1930. Other Useful Types of Maps • Aerial Photography – Vertical photography from mid 1930s to present; developed during WWII 1952 – Great for context – Distortion/displacement: scale, relief, and tilt – Use building footprints not rooftops, street intersections, 2001 etc. for control points Boston 1952 USDA aerial photo over 2001 MassGIS color orthophoto Other Useful Types of Maps • Map to Map Georeferencing – Compare one map to another – Don’t need real-world coordinates Map of Paris, 1832 Map of Paris, 1865 Georeferencing Techniques for Historic Maps • Use existing coordinates or tics • Link features on map to features within GIS datasets that have known real-world • Global Positioning System (GPS) Global Positioning System (GPS) A system of satellites & receiving devices used to compute positions on the Earth Global Positioning System (GPS) Collect ground control points for significant features on the map: building corners, street intersections, monuments, site remains, etc. Lat/Long 1815 map of early 16th century waterworks in Istanbul Global Positioning System (GPS) • Useful for georeferencing when one does not have any reference data or coordinates on the map • Primarily used for city-scale or larger scale maps, not for maps of very large regions Georeferencing Techniques and Historic Maps for GIS • Use existing coordinates or tics • Link features on map to features within GIS datasets that have known real-world coordinates • Global Positioning System (GPS) Rubber Sheeting • Expression is used many different ways Rubber Sheeting • “The process of transforming an image from one x,y coordinate system to another” – ArcInfo manual – Includes linear (Affine) transformations Rubber Sheeting • Higher order transformations (warping) – 2nd order or higher (nonlinear) that transform through curves – Need minimum of 6 control points – Maps of large areas and unknown projection – Aerial photography Rubber Sheeting • Piecewise Transformation – Uses different transformations in different parts of the map – Used when map is badly warped and data matching is essential – Used for edge-matching – Generally use a full transformation first – How does one record this in the metadata? – Sometimes easier with vector data Rubber Sheeting - What to Do? • • • • Start with a first-order (Affine) transformation Research projection of your map Find good control points Understand there is a fuzziness of inaccuracy in all maps and GIS data. • Then move on to higher order transformations and then piecewise transformations Getting Started Source Materials • Historic & contemporary maps – – – – – Map & government document libraries Special collections Archives Government agencies Commercial vendors • GIS data – – – – Government agencies Universities Libraries Commercial vendors Getting Started Software • Image processing software – Adobe Photoshop, Photoshop Elements • GIS software – ArcView, ArcGIS, IDRISI, AutoCAD, etc. • Advanced spatial image processing software (optional) – ArcInfo Grid, Spatial Analyst, ERDAS Imagine, etc. • Advanced wavelet image compression software (optional) – If want to disseminate georeferenced maps – ECW, MrSID, JPEG2000 Getting Started Hardware • Computer with minimum 512 megs RAM • For large processing 1-2 gigs of RAM • Access large format scanner or overhead digital photography Getting Started People • GIS skills – Usually takes about 1 to 2 weeks to get up to speed Do you need to bring your historic map into a GIS? • Maybe NOT – Making a map of an historical period. – Using the map as reference to encode preexisting GIS data. – Digitizing tablet • to extract/trace features. General Future of Bringing Historic Maps into GIS • History of cartography community needs more research concerning technical aspects (i.e., map projections and coordinate systems), mentioned by David Woodward at ICHC 2003 • GIS community needs to develop more historic projections, coordinate systems, and transformations. • Development of geo-historical datasets that can be widely used – must include metadata • Accuracy assessment • Outreach concerning the use and significance of historical materials for GIS Future of Bringing Historic Maps into GIS at the Harvard Map Collection • Harvard Library Digital Initiative – Georeferencing and disseminating maps online through the Harvard Geospatial Library (HGL) as JPEG2000 – Civil War collection – Early Africa – Chinese topos – Historic USGS topos • Experimenting with automated raster to vector data conversion • Conducting workshops and developing instructional materials concerning GIS and the humanities/social sciences Useful Internet Sites • The Harvard Map Collection – http://www.hcl.harvard.edu/maps/ • Harvard Geospatial Library – http://hgl.harvard.edu • David Rumsey Map Collection – http://www.davidrumsey.com/index.html • The Boston Atlas – http://www.mapjunction.com/places/Boston_BRA Comments and Questions?